As part of an aircraft engine design, gearboxes are subjected to competing criteria. For example, on one hand it may be desirable to use light-weight materials as part of the gearbox hardware in order to reduce aircraft weight. On the other hand, the gearbox materials must be sufficiently strong/durable in order to withstand various loads. Fan blade out (FBO) loads are often the limiting factor as part of a conventional gearbox design. FBO loads are the imbalance loads that the gearbox may experience based on a fan blade becoming detached from a fan hub/rotor.
As part of more modern gearbox designs, fuses are incorporated in an effort to avoid over-designing the gearbox hardware (e.g., in order to avoid adding excessive weight to the gearbox to protect against a rare FBO event). Such fuses are designed in pins or bolts with a small, tight tolerance notch added to a pin to provide a break point. The challenge in the use of such a fuse is that the fuse has to be able to withstand icing loads without being triggered/tripped. Often, machining tolerances on the notch limit the effectiveness of the fuse.